Monday, December 21, 2015

Hemlocks--still here but under assault

Holiday preparations clearly are affecting both my writing
and photographic time this week. I love
Christmas, but I am ready for the event itself and for the preparations for the
event to end. I hope that once the
holiday is over, my days will return to normal, so I can spend more time
writing and taking photos again.

The photo today was not taken at my cabin but in Michaux
State Forest. This is, I believe, a
little feeder stream into Tom’s Run. It’s
already been a week since I was there and I’m only now downloading the
photos. One thing I noticed on my walk
that day was that live hemlocks, Pennsylvania’s state tree, can still be found
in abundance.

The state’s trees are under assault by something called the
wooly adelgid, which sucks fluid from the base of the hemlock needles,
eventually killing the tree. They look a
lot like wooly aphids that can infect houseplants. Like so many other devastating pests, this
one is not native to North America. It
came from Japan, and our native hemlocks have no immunity against it. And like wooly aphids, the pest can be killed
with a soap/oil mixture. Unfortunately,
the preventative needs to be applied at least once a year, not to mention just
how does one spray all the hemlock trees in a forest?

Currently, the pest is found in 56 of Pennsylvania’s 67
counties. They can kill a tree in 4-10
years without treatment. The state is
moving ahead with the soap/oil treatment and is apparently thinking about
introducing a beetle that can kill the adelgid.
This worries me, as I can only hope the beetle doesn’t end up causing
other problems, as so often happens. The beetles are expensive, too, I’m
told.

The hemlock is a foundation tree in our forests. A healthy
tree supports many other animal and insect species. Clearly, a forest without hemlocks would not
support the same species as a forest with hemlocks. A forest without hemlocks would be an
entirely different ecosystem.

On my walk, I did see some dead hemlocks—most looked to have
been dead for years and may well not have died from this pest. The other hemlocks I saw still appeared
healthy, at least for the moment. I hope they stay healthy. I can’t imagine a Pennsylvania forest without them.

4 comments:

We have some high-and-dry hemlocks planted near our parking lot. They had adelgids, and we treated them many years ago with a systemic insecticide via a soil soak. The adelgids disappeared, the trees are healthy, and the insects have not returned.

Scott: I think the local forest people are trying to stay with a natural hemlock insecticide for the adelgids--the soap mixture--but also one that is cost effective for the whole forest. I'm glad to hear the bugs haven't returned to your trees, and I sure hope it stays that way!

Pablo: I guess the changes wrought by man and modern transportation just never end. I sure hope we can win the war against hemlocks and dogwood. I'd miss bananas, too. I keep hoping they find a strain of disease resistant chestnut and elms. A few years ago there was some promise with the chestnuts, but I haven't heard anything since, so perhaps that didn't pan out, after all.

About Me

I live in a cabin in the forests of Pennsylvania. I write about what I see and do in the natural world around me. I've been a hawkwatcher for more than 20 years, a birder for longer than that, and a crayfish-catcher since I was a polywog.